A light-emitting sensor device is provided with a substrate (110); an irradiating part (120), disposed on the substrate, for applying light to a specimen; a light receiving part (150), disposed on the substrate, for detecting light from the specimen caused by the applied light; a light scattering part, disposed at least one of between the irradiating part and the specimen and between the specimen and the light receiving part, for scattering at least one of light emitted from the irradiating part and the light from the specimen. The sensor device stably detects a predetermined type of information, such as a blood flow velocity, on the specimen.